567
FXUS61 KCLE 172358
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
758 PM EDT Wed Jul 17 2024

.SYNOPSIS...
A cold front will move southeast of the area tonight as a ridge
builds from the north-central United States and vicinity before
settling over the eastern Great Lakes and Upper Ohio Valley
this weekend.

&&

.NEAR TERM /THROUGH THURSDAY NIGHT/...
745 PM Update...
A few showers may persist along a trough axis over the next few
hours, but otherwise expect a downward trend in shower coverage
through this evening. Lake-enhanced clouds could move in
later this evening, but latest guidance suggests that the cooler
850mb temperatures and the greatest cloud cover may hold off
until mid-morning Thursday. Will need to continue to keep an eye
on upstream cloud cover (which isn`t widespread at the moment)
and adjust the forecast as needed. No changes needed with this
update outside of making minor adjustments to PoPs based on
latest radar trends.

Previous Discussion...
Cyclonic flow aloft and embedded disturbances affect the
eastern Great Lakes and Upper OH Valley, including our CWA,
through Thursday night. The cyclonic flow aloft is expected to
shift from W`erly to NW`erly late Thursday afternoon through
evening as a prominent mid/upper-level trough axis advances
SE`ward across our region. At the surface, a cold front in
vicinity of a New Castle, PA to Mount Vernon, OH line at 3:30 PM
EDT continues moving SE`ward and exits the rest of our CWA by
this early evening. Behind the front, a ridge associated with a
cooler/less humid air mass builds from the north-central United
States and vicinity. A lowering/strengthening subsidence
inversion accompanying the ridge will allow our sky to clear
gradually from northwest to southeast through the near-term
period. However, 850 mb temperatures cooling to near 9C to 10C
over ~24C Lake Erie and sufficient low-level moisture will allow
lake- effect stratocumuli to develop over and generally
southeast of Lake Erie late this evening through the mid-morning
hours of Thursday.

The aforementioned low-level cold/dry air advection regime will
contribute to cooler-than-average temperatures, overall.
Overnight lows tonight reach mainly the mid 50`s to lower 60`s
around daybreak Thursday. Highs are expected to reach the 70`s
late Thursday afternoon. Overnight lows are forecast to reach
the lower 50`s to lower 60`s around daybreak Friday. The warmest
of these lows are expected over/very near Lake Erie.

Primarily fair weather is expected during the near-term period.
However, daytime heating of the relatively-humid boundary layer
ahead of and behind the cold front has allowed mixed layer CAPE
to build to weak to moderate magnitudes amidst moderate
effective bulk shear in our CWA. Multicell showers/thunderstorms
along the surface to roughly 850 mb portion of the cold front
will exit our region generally to the east through this early
evening. In addition, isolated multicell showers/thunderstorms
associated with a shortwave disturbance`s attendant surface
trough axis/wind shift will overspread our northwest OH
counties from the west late this afternoon/early this evening.
This convection is expected to persist generally E`ward into
north-central and portions of northeast OH before dissipating
around sunset this evening, in response to boundary layer
stabilization via nocturnal cooling. Lastly, lake-effect
stratocumuli streaming generally SE`ward from Lake Erie may
produce rain showers during the predawn through mid-morning
hours of Thursday. These rain showers are expected to be light
since a lowering/strengthening subsidence inversion and low-
level dry air advection will likely limit lake-induced CAPE to
weak magnitudes.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Quiet and seasonable weather is expected for the short term period
as high pressure remains firmly in place. It may feel like late
Spring rather than mid-Summer at times with dew points in the 50s
under mostly sunny skies. Temperatures will be the coolest on Friday
night, with lows bottoming out in the 50s.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Mainly quiet weather will continue for the long term period as weak
surface high pressure remains in place, though chances for showers
and storms will percolate back into the region by Tuesday and
Wednesday as humidity increases ahead of a weak upper-level trough.
Not anticipating anything too organized on Tuesday and Wednesday as
mid and upper flow remain weak, though high atmospheric moisture
content and slow-moving storms could result in localized heavy rain.
Temperatures are expected to remain seasonable through the long term
period.

&&

.AVIATION /00Z Thursday THROUGH Monday/...
VFR should persist at all TAF sites for at least the next
several hours before lake-enhanced clouds begin to move in later
tonight and especially during the day Thursday. As of now,
guidance isn`t super aggressive with lower ceilings; instead of
MVFR ceilings, it`s possible that ceilings remain around 4-5kft
AGL and end up being more scattered since lake-induced
instability will be marginal. The highest cloud cover will
likely be mid-morning through Thursday afternoon when the
coolest 850mb temps arrive from the north. Can`t rule out some
patchy fog at southeastern terminals overnight where winds
become light overnight (including KCAK and KYNG), but the better
opportunity for non-VFR conditions will lie to the southeast of
the forecast area. Would like to see how fog develops before
introducing to any TAFs.

Winds will be out of the north at 6 to 12 knots, but as stated
above, winds at KMFD/KCAK/KYNG will likely drop below 5 knots
overnight tonight.

Outlook...VFR expected Thursday afternoon through Monday.

&&

.MARINE...
A mainly quiet marine period is in store through the weekend with no
headlines anticipated. Only timeframe we`ll need to monitor for
slightly higher winds/waves will be behind a cold front tonight into
Thursday, as winds shift towards the north, around 15 knots,
ushering in waves 2 to 4 feet. Following Thursday, surface high
pressure is expected to remain firmly in place across the region
through the weekend, with periods of light flow less than 10 knots
expected.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...Jaszka/Maines
NEAR TERM...Jaszka/Maines
SHORT TERM...Kahn
LONG TERM...Kahn
AVIATION...Maines
MARINE...Kahn